Burster-igniter device



.1969 W..G.SWEET,MAN 3,

BURSTER-IGNITER DEVICE Filed Dec. 20, 1965 INVENTOR.

William 6. Sweetman United States Patent 3,482,518 BURSTER-IGNITER DEVICE William G. Sweetman, Houston, Tex., assignor, by mesne assignments, to the United States of America, as represented by the Secretary of the Navy Filed Dec. 20, 1965, Ser. No. 515,214 Int. Cl. F42c 19/08 U.S. Cl. 102-70 Claims This invention relates generally to a device for igniting a fire package and more specifically to a bursterigniter device particularly adapted for use with a special floating fire package having designated military application'. The flotation principle of the special floating fire package is similar to that of a life jacket using foam, so designed that punctures will not cause sinking, and in which the attitude of the container thereof is controlled by a counterweight. The unit can be loaded with various fuels, such as gasoline, JP4, napalm mixes and many others. In all past burster-igniter devices dealing with the ignition of a napalm unit on water, both a high explosive burster tube and another container of sodium were required in order to successfully ignite the napalm or other fuel being used.

The principal object of the invention is the provision of a new and improved burster-igniter device that will eliminate the necessity for having the sodium and high explosive components in such floating fire packages.

Another object of the present invention is the provision of a burster-igniter device including means whereby the device may be quickly attached to a container for a floating fire package and thereafter fired at will for igniting the fire package.

Another object of the present invention is to provide a new and improved burster-igniter device which is economical to manufacture, reliable in operation and which possesses the qualities of durability during handling and transportation.

Accordingly, the burster-igniter device of the present invention comprises an elongated cylindrical-shaped nylon tube closed at one end and having packed therein a length of black igniting powder, a quantity of boron pellets scattered throughout the length of powder, a strip of magnesium passing therethrough and a small foam plug positioned between the powder and the closed end of the tube. A small amount of initiating powder is placed at the open end of the tube separated from the igniting powder by an aluminum disc and adapted to be secured to the tube by an actuating member incorporated within the floating fire package. In the aforedescribed device, the foam plug compresses just before the critical bursting point for the particular tube is reached, thus permitting the powder to burn further, but not completely, and when it ruptures there is still an interface of flame between the burned and unburned powder which ignites the fire package after the tube bursts.

The exact nature of this invention as well as objects and advantages in addition to those already mentioned will be readily apparent from consideration of the following specification when taken in connection with the accompanying drawing, wherein the single figure thereon shows a central longitudinal sectional view of a preferred embodiment of the present invention.

Referring now to the drawing, there is shown a cylindrical tube generally designated by the reference numeral 10 and being composed preferably of nylon and being closed at one end 12 and open at the other end 13. The outer peripheral wall of tube 10 is threaded near the end portion 13 thereof for receiving thereon in threaded engagement a top plug member 15 which may be composed of stainless steel or any other suitable metallic material and which is designed for incorporation into the floating fire package.

Plug 15 is a substantially cylindrical member having an axial bore 16, a first counterbore 17 facing one end of the plug and cooperating with the axial bore 16 to define a shoulder 18, a second counterbore 19 cooperating with counterbore 17 to define a shoulder 20, and a third counterbore 21 facing the other end of the plug and cooperating with axial bore 16 to define a tapered shoulder 22. The plug 15 is provided with internallythreaded portions 24 and 25 at either end thereof in counterbores 19 and 21, respectively, and with an externally-threaded portion 26 substantially midway along the axial length thereof. During transportation and normal handling of the device a protective screw cap 28 is secured within the counterbore 21 threadably engaging the threaded portion 25 therein. An annular gasket member 29 composed of rubber or the like is secured between the head portion of screw cap 28 and the end wall of the top plug 15 and is compressed therebetween upon tightening of the screw cap 28 to provide sealing of the plug 15. This sealing may be made even more effective if an adhesive is first applied to the end wall of plug 15 receiving the annular gasket 29 and to the side of the gasket which abuts that end wall.

Within the top plug member 15, a thin aluminum disc 31 having substantially the same diameter as that of counterbore 17 is positioned within the counterbore 17 and is secured to the shoulder 18 by an epoxy adhesivesealant or other suitable means. The cavity within the plug 15 defined by the counterbore 17 is then filled with an initiating powder 32 such as, for example, FFF-G black powder and a second thin aluminum disc 33 having substantially the same diameter as that of counterbore 19 is positioned within the counterbore 19 against the shoulder 20 therein. Disc 33 serves to contain initiating powder 32 within the cavity of counterbore 17 and may be secured in place by an adhesive-sealant similar to that employed with disc 31. Although the discs 31 and 33 have been described as being composed of aluminum, it is to be understood that they might be constructed of other suitable light-weight metallic materials.

A small foam plug 35 composed of a closed-cell polyurethane such as, for example, Ethafoam, is positioned Within the cylindrical nylon tube 10 in abutting relation with the closed end thereof. The remaining length of the tube 10 is filled with a black igniting powder 36 such as, for example, FIG. FG black powder having dispersed therein a quantity of boron pellets 38, and a strip of magnesium ribbon 37 secured at one end by compression thereof between the foam plug 35 and the inner peripheral wall of the nylon tube 10 is positioned within the powderfilled tube extending substantially along the entire length of the tube. The open end 13 of igniter tube 10 is effectively closed when the top plug member 15 is threadably secured thereon, whereupon the disc 33 is contacted by the annular end wall of the tube 10 and is urged into even tighter engagement with shoulder 20 within the plug 15.

The externally-threaded portion 26 on the top plug member 15 is provided for the purpose of securing the burster-igniter device within the fire package in which it is to be used. A flange element 39 and an O-ring 40 are shown in the drawing and are adapted for matingly engaging the fire package container in a sealed relationship therewith.

One of the most unique features of this device is the simplification of the burster-igniter, which eliminates the sodium and high explosive components required in all past burster-igniters dealing with the ignition of a napalm unit on water. When readying the present device once it is installed in a fire package, it is only necessary to remove the shipping plug or protective screw cap 28 and to replace it with either a mechanical firing plug or an electroresponsive initiator, as may be desired, and which when installed will engage tapered shoulder 22 and abut the thin aluminum disc 31. The ignition of the initiating powder 32 within the plug member 15 can of course be brought about by many means having small flaming outputs, such as conventional squibs and similar delay-firing devices. Subsequent ignition of the length of igniting powder 36 takes place upon failure of the thin aluminum disc 33, and bursting of tube and ignition of the fuel within the fire package follows thereafter. Upon the rupture of the tube 10, the pellets 38 are scattered a greater distance and will maintain their temperature for a greater period of time than the black powder, a feature found desirable with certain incendiary mixtures.

It should be observed that if the burster-igniter tube 10 of the device disclosed herein were fully loaded with the same amount of black igniting powder 36, but without the foam plug 35, there would be an inconsistency as to the amount of powder that would burn. Tests have shown, for example, that approximately half the length of powder 36 would be burned and the remaining length would remain hardpacked and unburned. If the strength of the tube were increased to permit additional burning prior to bursting of the tube, the result would merely be complete burning of the powder accompanied by a violent explosion. The secret, therefore, of getting igni tion plus acting as a burster and igniter, and a novel feature of this invention, is that just before reaching the critical bursting point of the tube 10, the foam plug 35 is compressed by the force of the pressure generated therein, thus allowing the powder 36 to burn on further, but not completely, so that when tube'10 ruptures there is still an interface of flame between the burned and unburned lengths of powder 36 that brings about ignition of the napalm or other fuel within the fire package after the bursting of tube 10.

What is claimed is:

1. A burster igniter device for use with a fuel container comprising:

a cylindrical tube closed at one end and open at the other end thereof,

a compressible foam plug positioned within said tube adjacent the closed end thereof,

igniting powder substantially filling said tube between the foam plug and the open end of said tube,

a magnesium ribbon positioned within said igniting powder and extending substantially along the entire axial length of said tube,

means for closing the other end of said tube, and

means for initiating said igniting powder.

2. A device according to claim 1 wherein said tube is composed of nylon.

3. A device according to claim 1 wherein said foam plug is composed of a closed-cell polyurethane.

4. A device according to claim 1 wherein said igniting powder is an F-G black powder.

5. A device according to claim 1 wherein said initiating means is an FFFG black powder.

6. A device according to claim 1 wherein said end closure means for said tube comprises a plug member threadably engaging said tube about the open end thereof.

7. A device according to claim 6 wherein said plug member includes means therein separating said initiating means and said igniting powder.

8. A device according to claim 7 wherein said separating means is a thin aluminum disc.

9. A device according to claim 8 wherein said plug member is provided with a normally-closed passageway communicating with said initiating means and adapted for receiving therein means for activating said initiating means.

10. A device according to claim 1 wherein said end closure means for said tube comprises a metallic plug member threadably engaging said tube about the open end thereof,

said plug member having an axial bore therethrough,

a first counterbore containing said initiating means and a second counterbore for receiving said tube therein,

a first disc member positioned within said plug member and separating said initiating means from said igniting powder, and

a second disc member positioned within said plug mem ber and retaining said initiating means within said first counterbore.

References Cited UNITED STATES PATENTS 2,310,344 2/1943 Barab 10224 2,685,835 8/1954 Noddin et al. l0228 2,965,032 12/1960 Borcher et al 10222 2,990,683 7/1961 Walden 102-702 3,086,894 8/1963 Baggett et al 10270.2

3,211,094 10/1965 Liddiard 10224 X BENJAMIN A. BORCHELT, Primary Examiner J. FOX, Assistant Examiner US Cl. X.R. 

1. A BURSTER IGNITER DEVICE FOR USE WITH A FUEL CONTAINER COMPRISING: A CYLINDRICAL TUBE CLOSED AT ONE END AND OPEN AT THE OTHER END THEREOF, A COMPRESSIBLE FOAM PLUG POSITIONED WITHIN SAID TUBE ADJACENT THE CLOSED END THEREOF, IGNITING POWDER SUBSTANTIALLY FILLING SAID TUBE BETWEEN THE FOAM PLUG AND THE OPEN END OF SAID TUBE, A MAGNESIUM RIBBON POSITIONED WITHIN IGNITING POWDER AND EXTENDING SUBSTANTIALLY ALONG THE ENTIRE AXIAL LENGTH OF SAID TUBE, MEANS FOR CLOSING THE OTHER END OF SAID TUBE, AND MEANS FOR INITIATING SAID IGNITING POWDER. 